Purple on the edges of color film

[Mexipike]

I'm working with someone who has a collection of 8x10 color negatives which were processed by a reputable lab in Los Angeles. A large amount of them have purple bleeding in on the edges. These are over various different film holders, and not a result fo the scan and on the actual negatives themselves. The film was fresh.

Anyone have any ideas on what could cause this?

I've included a low res sample but you should get the idea. Many of them have this purple on both sides.

Thanks!